Multistage fuel mixer



Dec. 10, 1929. w, MCKEE MULTI STAGE FUEL MIXER Filed Feb. 26, 1927 Patented Dec. 10, 1929 GARNET W. MOKEE, OF ROCKFORD, ILLINOIS MULTISTAGE FUEL mxnn This invention pertains to devices used for mixing fuel gas and air to form combustible mixtures.

Single stage mixers are found to be quite.

suitable for certain purposes but for other uses experience has taught that the single stage fuel mixers do not mix the gas and air with quite as high efficiency and thoroughness as is necessary for the required economies of operation. In order that a two stage mixer be of practical use, it should be simple in construction, it should not beso designed as to accumulate any foreign matter and become clogged therewith and it should not require such adjustment as would necessitate the attention of skilled operators.

One of the objects of this invention is to provide a fuel mixing device having means formixing gas and air and means for adding to the first mixture a further amount of air and thoroughly mixing the same.

'Another object of this invention is to provide a two-stage fuel mixing device having a single adjustment for regulating the two sta es of mixing.

nother object of this invention is to provide in a single fuel mixing device, a regulatable means for mixing gas and air and a nonadjustable means for mixing gas and air, the two means cooperating to produce a mixture of gas and airof predetermined desired proportions.

Another object of this invention is to provide in a fuel mixing device a manually adjustable means for mixing gas and air and another means for mixing gas and air which is not manually adjusted, the valve operation of the first means servin to variably control the mixing performed y the second means. a.

Another object of this invention is to provide a fuel mixing device having the above mentioned capabilities and so constructed that its various parts may be easily and quick- 1 replaced bysimilar corresponding parts of the samea'sizes or of difi'erent sizes for repair purposes and for varying the capacities of the device. I

Another object of this invention is .to provide a-multi-stage fuel mixing device whose Application filed February 26, 1927. Serial No. 171,882.

simplicity of construction lends itself to economical manufacture and to minimum maintenance costs, and which does not require the services of skilled operators for its efiicient use.

Referring now to the drawing which illustrates an embodiment of my inveiition,

Fig. 1 is a longitudinal vertical sectional view of the entire two-stage fuel mixer;

Fig. 2 is a vertical central section of a portion of the same mixer on an enlarged scale; and' Fig. 3 is a transverse vertical section taken on the line 3-3 of Fig. 2.

Referring now in greater detail to the 5:; drawing, a casing 1 having an outlet port 2 is adapted to retain within it a gas intake member 3.

Gas is introduced through the port 4 into the intake member 3, into the gas intake 7 chamber generally indicated as 5, and is permitted to escape in regulatable quantities through the gas outlet port 6.

The size of the gas outlet port 6 is determined by the size of a-jet 7 which isremovably inserted. into the wall of the gas intake member 3, as illustrated.

'. In order that the fiow' of gas through th port 6 may be regulated, a needle valve 8 may be advanced toward or withdrawn from the so seat 9 of the jet 7. The needle 8 is integral with a screw 10 which may be rotated by means of a screw driver or in some other suitable manner. The screw 10 is provided with an exterior thread 11 which cooperates with internal threads 12 on the guide member 13,

which is formed integrally with the gas intake member 3.

In order that air and fuel gas may be proportionately mixed to form combustible mixtures, gas under pressure is introduced through the port 4 into the gas intake chamber 5 and is permitted to escape through the port 6. As it escapes through the port 6, the rapidly flowing stream of gas causes a reduction of pressure in its immediate vicinity and entrains along with it in proportion to the speed, volume' and density of the stream of gas, a uantity of air which'is permitted to flow in t rough the air inlet port 14, which is provided in the casing 1. The shutter 15 may be advanced by rotation on the external threads of the guide member for regulating the efiective opening around the port 14. Once this shutter is positioned to give a desired proportion between the gas and the air, it is clamped in that position and the quality of the combustible mixture will remain the same thereafter while the amount of gas entering theport 4 is being increased and decreased Within reasonable limits by a valve external to this fuel mixer.

It will be observed that within the mixer itself, there are provided means for regulating the size of the gas outlet port and means for regulating the size of the air intake opening. The cap nut 16 is used to close the open end of the guide member and to lock the shutter 15 in any desired position.

The projected stream of gas from the port 6 is directed squarely toward the center of the channel 17 in the primary Venturi tube 18 and as it enters the tube 18 it entrains air through the port 14. This tube 18 expands slightly toward its delivery end 19 and mixes the gas and air as it conducts them toward its end 19. As this'first mixture of gas and air emerges from the open end 19 of the primary Venturi tube, it also entrains quantities of the air located near and surrounding that'open end 19. This second entraining action causes a flow of air through the channels 20 and this secondary amount of air mixes with the primary mixture as they both flow into the Venturi tube 21, the ultimate result 1 being a combustible mixture very efficiently mixed and within a wide range of operating requirements very accurately proportioned. The channel 22 in the Venturi tube 21 is of sufficientv length and so designed as to cause a thorough mixing of the gas and air.

It will be observed that for producing the second stage of mixing, no special adjusting mechanisms are required for that stage of the operation. It is found that when this mixing device is well designed and proportioned for a given task, for a single setting of the needle 8 and the shutter 15 the mixtures ultimately produced by this device are very accurately proportioned within very wide ranges of burner capacities. The fins 23 which support the primary Venturi tube constitute a very slight restriction in the passage and accumulate no foreign matter. This device is therefore entirely free from operating defects and not only has a satisfactory low cost of manufacture but an unusuallyhigh efiiciency of operation.

As illustrated, the primary Venturi tube is connected to the casing 1 by threads and the secondary tube is connected to the primary tube likewise by threads. This simple manner of connecting the several parts makes them readily replaceable by new parts or parts of difierent sizes and also contributes materially to standardization in manufacture.

To operate the mixer, the needle 8 and the shutter 15 are set in the proper positions to give the correct mixture, it being, of course, possible to set them either when the device is idle or when in use. A setting having been made the quantityof gas under low, medium or high pressure is admitted into the port 4, the entering flow of this gas being regulated by a valve external to and independent of the mixer. The projected. stream of gas from the port 6 entering the primary tube not only entrains a proportional amount of air into the primary tube, but it also sets up a general forward movement of air in the chamber within the casing 1, thus aiding the entraining action taking place at 19 where the primary mixture emerges from the primary tube. Thus, the setting of the needle 8 and the shutter 15 not only proportions theprimary mixture but it also proportions the secondary or'ultimate mixture.

It should be understood that the illustrated embodiment of my invention is subject to considerable modification and change without departing from the spirit and scope of my invention.

1 claim:

1. A gas mixing device comprising a casin forming a chamber, regulatable means in sai chamber for regulatably directing a stream of gas into said chamber, a primary shell detachably connected to said chamber having a primary Venturi tube longitudinally disposed within its walls, an open end of said primary tube being adapted to directly receive said stream of gas and to receive a quantity of atmospheric air entrained by said stream, regulatable means for admitting atmospheric air into said chamber, a passage in said shell alongside said primary tube communicating with said chamber and having an open end in proximity to the delivery end of t e primary tube, the delivery of the fluid mixture from the primary tube being adapted to entrain additional atmospheric air past both ends of said tube from said passage to form the ultimate mixture of gas and air, and a secondary Venturi tube detachably connected to said shell adapted to receive a fuel mixture from the primary tube and auxiliary air from said passage and to completely mix said air and mixture within the tube.

tube into one end of which said gas is discharged, and a secondary Venturi tube detachably connected to said shell aligned with the primary tube to receive the discharge from the primary tube, and regulatable means for admitting atmospheric air to said chamber, the gas stream being adapted to entrain a supply of air into the primary tube wherein said air and gas are uniformly mixed, the resultant mixture being adapted to entrain into the secondary tube additional air from the chamber ast the primary tube for complete and uni orm mixing of the last said air with said mixture. I a

3. A gas mixing device comprising a casing forming a chamber, means in said chamber for admitting a flow'of gas into said chamber, a primary shell removably connected with said casing and having a primary Venturi tube disposed within its walls, said primary tube being adapted to directly recelve said stream of gas and to receive a quantity of at- 1 mospheric air entrained by said stream and to uniformly mix the air and gas during'their passage therethrough, regulatable means for admitting atmospheric air into said chamber, a assage in said shell communicating with said chamber and having an open end in proximity to the delivery end of the primary tube for conducting additional 'air admitted through said air regulating means to be entrained upon the mixture dischar ed from the primary tube, and a secondar enturi tube removably connected with sai primary shell adapted to thoroughly and uniformly mix said additional air with the mixture of gas and air discharged by said primar tube.

In witness of the foregoing I a x my slgnature.

GARNET W. MoKEE. 

